The wireframe view can be chosen by clicking on the text in the upper left corner of each viewpoint.
The texture selector is on the right (It's the browse button) and the tools used to apply textures are in the main toolbar.

Try verifying the integrity of SDK's cache (right-click the SDK, properties, Local Files, Verify Integrity of Tool Cache) if you're having trouble with the viewports not working in the first place (which it looks like you are).

Viewport errors are usually a result of game config or steam filesystem errors. Looking at the directory path in Hammer's title bar, it looks like you are using the pirated SDK which probably means none of our ideas will be useable. Go ask for help from the people who put together the pirate SDK.

2xzzy:
Some russian mappers use Ultimate SSDK. USSDK-extended edition with all mapping and modelling tools. USSDK can work with pirated content of valve's games.2A Boojum Snark:
No. I use the license ssdk for mapping for TF2.